The magnitude of the electric force between two charged particles is determined by Coulomb's law, which states that the force is directly proportional to the product of the charges and inversely proportional to the square of the distance between them.
If we double the amount of charge in each particle, the electric force between them will also double. This is because the force is directly proportional to the product of the charges. Increasing both charges by a factor of 2 will result in a force that is 2 times greater.
Next, if we double the distance of separation between the particles, the electric force will decrease by a factor of 4. This is because the force is inversely proportional to the square of the distance. Increasing the distance by a factor of 2 will cause the force to decrease by a factor of (2^2 = 4).
Therefore, if we first double the amount of charge in each particle and then double the distance of separation, the overall effect on the electric force will be a decrease by a factor of 2 (due to the increase in distance) and then an increase by a factor of 2 (due to the increase in charge). As a result, the net effect would be no change in the magnitude of the electric force.